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capi: Fix 'unused return value' warnings #882

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merged 2 commits into from
Jul 14, 2022
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rhysd
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@rhysd rhysd commented Jul 14, 2022

cargo check --workspace reported the following warnings on my local machine.

warning: unused return value of `alloc::ffi::c_str::CString::from_raw` that must be used
   --> regex-capi/src/rure.rs:261:17
    |
261 |                 CString::from_raw(ptr);
    |                 ^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `#[warn(unused_must_use)]` on by default
    = note: call `drop(from_raw(ptr))` if you intend to drop the `CString`

warning: unused return value of `alloc::ffi::c_str::CString::from_raw` that must be used
   --> regex-capi/src/rure.rs:627:18
    |
627 |         unsafe { CString::from_raw(s); }
    |                  ^^^^^^^^^^^^^^^^^^^^^
    |
    = note: call `drop(from_raw(ptr))` if you intend to drop the `CString`

warning: `rure` (lib) generated 2 warnings

This PR fixes the warnings.

Environment

  • rustc: 1.62.0
  • cargo: 1.62.0
  • OS: macOS 11.6.7

@rhysd
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rhysd commented Jul 14, 2022

Note: The #[must_use] changes were added at Rust 1.57: rust-lang/rust#89692

while let Some(ptr) = it.name_ptrs.pop(){
CString::from_raw(ptr);
while let Some(ptr) = it.name_ptrs.pop() {
drop(CString::from_raw(ptr));
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We might as well go the whole nine yards here and add drop(..) around other calls to from_raw as well. e.g., Box::from_raw. Would you mind doing that as well?

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Thank you for the review comment. I searched Box::from_raw and applied the same fix at 1324f2d

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Perfect, thanks!

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2 participants